The workers here attack and kill Solenopsis aurea/amblychila. Sometimes a Solenopsis worker will just be out exploring for food, and suddenly one Brachymyrmex worker runs up to her (even though she wasn't even close by) attack her and it only takes one Brachymyrmex to kill one Solenopsis worker. Usually the Brachymyrmex team up and surround the worker(s) and kill them. Then, a Forelius mccooki was out exploring, going back to her nest. Suddenly a bunch of Brachymyrmex workers surround her and kill her as well. Then there was an Argentine ant colony (a small one) and a bunch of Brachymyrmex went in and invaded it, and then no more Argentine ant colony. Instead it became a Brachymyrmex colony. Then they also attack Monomorium ergatogyna, they really dislike them. However, once the M. ergatogyna get a big colony they get left alone.
The only two ants they leave alone are Pheidole megacephala (which they ignore) and Dorymyrmex bicolor (which they also ignore). But, a lot of ants around here get randomly attacked by the Brachymyrmex workers. And the Brachymyrmex worker(s) will travel from 5-7 seconds away just to kill the other ants.
Last year, they didn't behave like that at all. They DID act aggressive toward Argentine ants when defending, but they didn't actually attack their nests.
This year, on average most colonies have doubled, tripled and one location have grown four times their number of colonies and number of ants compared to last year.
Seems over time they are becoming a lot more aggressive. They (at least here in Irvine, Southern California) are also growing in numbers every year, and becoming more aggressive as a result.
Not sure about other locations they can be found in, but the Brachymyrmex patagonicus in my neighborhood are becoming like Argentine ants.
